Developing agent precursors of cyclohex-2-ene-1,4-diones

ABSTRACT

PHOTOGRAPHIC DEVELOPING AGENT PRECURSORS, USEFUL FOR EXAMPLE, FOR INCORPORATION IN PHOTOGRAPHIC ELEMENTS, ARE PROVIDED IN THE FORM OF CYCLOHEX-2-ENE-1,4-DIONES AND MONOKETALS THEREOF. THESE CAN BE PREPARED FOR CORRESPONDING 5,8-METHANO -2,3,4A,5,8,8A - HEXAHYDRO - 1,4NAPHTHOQUINONES OR CORRESPONDING MOMOKETALS BY PYROLYTIC DECOMPOSTION.

United States Patent Ofice 3,586,506 Patented June 22., 1971 3,586,506 DEVELOPING AGENT PRECURSORS F CYCLOHEX-2-ENE-1,4-DIONES Derek D. Chapman, John W. Gates, Jr., and Walter J. Mnsliner, Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, NY. No Drawing. Filed Mar. 27, 1968, Ser. No. 716,325 Int. Cl. G03c 1/76 US. Cl. 96-66 19 Claims ABSTRACT OF THE DISCLOSURE Photographic developing agent precursors, useful for example, for incorporation in photographic elements, are provided in the form of cyclohex-2-ene-1,4-diones and monoketals thereof. These can be prepared from corresponding 5,8-methano 2,3,4a,5,8,8a hexahydro 1,4- naphthoquinones or corresponding monoketals by pyrolytic decomposition.

The invention relates to photographic materials. In one of its aspects it relates to developing agent precursors, particularly for developing a latent image in an exposed photosensitive silver salt containing layer of a photographic element. In another of its aspects, the invention is directed to novel cyclohex-2-ene-1,4-diones and monoketals thereof and their preparation. In another aspect of the invention, such compounds are incorporated in photographic compositions, such as a photographic emulsion, a layer of a phostographic element, or a developer composition. A still further aspect of the invention relates to novel 5,8 methane-2,3,4a,5,8,8a-hexahydro-1,4-naphthoquinones or corresponding monoketals useful for preparing cyclohex-Z-ene-1,4-diones and corresponding ketals.

In one process of photographic development, an exposed photographic element comprising a support having at least one photographic silver salt layer thereon, is immersed in a developing bath containing a silver halide photographic developing agent. The developing bath is normally maintained as a separate processing bath and with continuous use, the bath usually becomes less eflicient so that special techniques and replenishments are normally required to maintain optimum processing efiiciency. The developing baths of the prior art normally contain a developing agent, a preservative, such as sodium sulfite, and alkali to activate the developing agent, and can also contain other materials, such as sodium bromide, antifoggants, etc.

In processes of this kind, it has been proposed to incorporate the silver halide developing agent directly in a layer of the photographic element. An image in a photosensitive layer of the element is developed by treating it with an alkaline solution which may or may not contain a developing agent. Following development, the developed silver image is fixed or stabilized by treating the developed silver halide layer in a conventional fixing or stabilizing bath. The developed and fixed photographic layer is then usually washed and dried. Although this is convenient, it is frequently disadvantageous because the developing agent may deteriorate on storage and may become ineffective after some keeping, or may migrate from the layer in which it is included.

Materials which can be employed as developing agents in solutions are not always satisfactory when incorporated in a layer of a photographic element since they may not be photographically inert, may diffuse undesirably to other layers of the element, may be undesirably unstable, may have undesirable solubility characteristics, and the like. It, accordingly, has been proposed to employ materials which are not developing agents, but are developing agent precursors which in the presence of a suitable activator, e.g. heat, alkali, or a combination of heat and alkali, form a developing agent.

In some cases, such developing agent precursors have provided problems similar to those encountered with developing agents, e.g. they may not be photographically inert, may diffuse undesirably to other layers of the element, may be undesirably unstable, and the like.

Certain compounds proposed heretofore as developing agents, not developing agent precursors, include dihydropyrogallol; coumarindiol; and 1,2,S-trihydroxynaphthalene as set out in U.S. Pat. 2,685,515 of Wilson, issued Aug. 3, 1954. US. Pat. 3,287,129 of Rees, Frauenglass and Gates, issued Nov. 22, 1966, on the other hand, sets out certain developing agent precursors which are Diels-Alder adducts, such as (a) 2-t-butyl-5,8-methano-4a,5,8,8a,-tetrahydro-1,4-naphthoquinone, and (b) 5,8-methano-2-isopropyl-4a,5,8,8a-tetrahydro 1,4 naphthoquinone. A disadvantage of such developing agent precursors is that they require strong alkalis to form developing agents within a reasonably short time. For instance, the described bridged tetrahydro-1,4-naphthoquinone compounds exhibit no developing activity with a sodium sesquicarbonate activator solution. It is also known that the compound:

is not a developing agent or developing agent precursor. Accordingly, there has been a need for developing agent precursors which decompose satisfactorily to form developing agents in the presence of a suitable activator, are photographically inert in a layer of a photographic element, are not unstable until they are contacted with a suitable activator, and the like.

There has also been a need for compounds and simpler methods for preparing such developing agent precursors. For example, it has been proposed to prepare cyclohex- 2-ene-1,4-dione by a multi-step reaction whereby hydroquinone is converted to 4-benzoyloxycyclohexanone in three steps (E. R. H. Jones and F. Sondheimer, J. Chem. Soc., 615, 1949) which is then transformed by ketalization followed, respectively, by (a) saponi'fication, (b) monobromination, (c) treatment with a chromium trioxidepyridine mixture, and (d) reaction of the resulting monoketal with sulfuric acid. (Garbisch, J.A.C.S., vol. 87, page 4971, 1965). A surprisingly simple pyrolytic method has now been found for preparing cyclohex-2-ene-1,4-dione compounds and corresponding monoketals which eliminates the several steps required heretofore.

It is an object of the invention to provide photographic silver salt developing agent precursors which can be incorporated in a photographic composition, such as a layer of a photographic element and which have desired stability and are photographically inert until treated with a suitable activator.

Another object is to provide photographic compositions which have such precursors incorporated therein.

A further object is to provide simplified methods for preparing cyclohex-Z-diones and corresponding ketals.

A still further object is to provide certain novel bridged hexahydro naphthoquinones and corresponding monoketals for preparing developing agent precursors.

The invention, accordingly, comprises photographic compositions, elements and processes employing a cyclohex-2-ene-1,4-dione developing agent precursor and/or corresponding monoketal developing agent precursor which is stable until contacted with a suitable activator, decomposes satisfactorily to form a developing agent in the presence of a suitable activator, is photographically inert in a layer of a photographic element and provides desired development in the presence of a suitable activator. It also comprises certain novel hexahydro naphthoquinones and corresponding monoketals and methods of preparing the described developing agent precursors from such bridged hexahydro naphthoquinones and corresponding ketals. It further comprises certain novel cyclohex-Z-ene- 1,4-diones and corresponding monoketals useful as the described developing agent precursors.

Developing agent precursors according to the invention include those represented by the formula:

Suitable halogens include chlorine, iodine and fluorine. Suitable alkyl radicals have from 1 to about 20 carbon atoms and are typically lower alkyl having 1 to 5 carbon atoms. Representative alkyl radicals are methyl, ethyl, propyl, isopropyl, butyl, t-butyl, pentyl, octyl, dodecyl, pentadecyl and eicosyl. Representative aryl radicals, having from 6 to 20 carbon atoms, include phenyl, tolyl, benzyl, Xylyl and the like. Suitable alkoxy radicals have from 1 to about 20 carbon atoms, preferably from 1 to about 5 carbon atoms, illustrative ones being methoxy, ethoxy, heptoxy, dodecoxy, and the like.

Examples of cyclohex-2-ene-1,4-dione and cyclohex-Z- ene-1-one-4-monoethylene ketal developing agent precursors are as follows:

A. O B. 0 C. D. 0

I] H I? ll Cl H300 H H H O 0 ll E. O F G. O H.

H H H CH3- (1? CH3 CH CH3 H502 CH2 CH3 H H H I J. O K.

CH3 CH2 (011302 CH -CH CH3 CH3 H H H L. 0 'M. 0 N.

H II 0 H II (CHa)zC-CH2 CH3 II I! CH3- 0 CHz\ 013mg II 0 0 0 0 A l l L l l R. O S. 0

II H

| l l i Cyclohex-Z-ene-1,4-diones and corresponding monoketals can be prepared by selective reduction of the cyclopentadiene adduct of a 1,4-benzoquinone or corresponding monoketal with, for example, zinc in the presence of acetic acid using the procedure set out in an article by K. Alder and G. Stein, Ann., vol. 501, page 247 (1933), to form a cyclopentadiene :adduct of a 1,4-quinone, or. corresponding monoketal, which by pyrolytic decomposition can form the desired cyclohex-2-ene-L4-dione or corresponding monoketal.

A method of preparation of cyclohex-Z-ene-1,4-diones Within the scope of the invention can be represented by the formulas:

wherein R, R and R" are each as described above. The reduction step can be carried out as described employing zinc and acetic acid. The pyrolytic decomposition step is similar to the procedure set out in Alder et al., described in Chem. Ber., volume 93, page 1896 (1960). The reactants are usually employed in stoichiometric quantities, but excesses can be employed if desired.

It was found that in compound III where R is phenyl or methoxy and R and R" are hydrogen that pyrolytic decomposition may occur causing formation of the cor responding hydroquinone, rather than the desired cyclohex-2-ene-1,4-dione.

Accordingly, a cyclohex-2-ene-1,4-dione can be prepared by mineral acid hydrolysis of a corresponding monoketal. A suitable method is represented by the following formulas:

acid hydrolysis (VII) comprising pyrolytically decomposing a compound of the formula:

VIII 0 R I wherein R, R and R are the same or different and each selected from hydrogen, halogen, and alkyl as described herein. This can be carried out under the conditions described for conversion of III to IV.

Cyclopentadiene adducts of 1,4-benzoquinones are set out, for example, in U.S. Pat. 3,287,129 of Rees et al., issued Nov. 22, 1966. These compounds, e.g. those Within described Formula II, can be prepared employing known procedures such as set out in an article by Alder et al., Chem. Ber., vol. 93, page 1896 (1960), or Wilgus et al., in Canadian Journal of Chemistry, vol. 44, page 603 (1966). For example, about stoichiometric quantities of a 1,4-benzoquinone and cyclopentadiene are refluxed in a suitable solvent such as benzene until reaction is complete. The desired product can be recovered, such as by dissolving the hot reaction product in hot ligroin and chilling. The product can be purified, such as by recrystallization from ligroin.

Suitable conditions for the described reduction of compound II to compound 111 include dissolving the cyclopentadiene-benzoquinone adduct in acetic acid at about room temperature, eg about 25 0., adding zinc dust, permitting the reaction to proceed until complete, e.g. about 10-15 minutes, and isolating the product, such as by crystallization or distillation.

The pyrolytic decomposition or so-called retrograde Diels-Alder reaction of compound III to yield compound IV is suitably conducted in a thermolytic distillation apparatus, the temperature at which reaction takes place being at about 125 C. to about 450 C., and at atmospheric or reduced pressure.

Another embodiment of the invention is a method of preparing a compound of the formula:

comprising pyrolytically decomposing a compound of the formula:

wherein R, R and R" are the same or different and each selected from hydrogen, halogen, alkyl, alkoxy, and aryl. This can be carried out under conditions set out in an article by Alder et al., Chem. Ber., vol. 93, page 1896 (1960). The pyrolytic decomposition, as in the case of reaction of compound III to yield compound IV, can be carried out in a known thermolytic distillation apparatus, the temperature at which reaction takes place being at about C. to about 450 C., and at atmospheric or reduced pressure.

The monoketals described, e.g. the monoketals represented by Formulas IX and X, can be hydrolyzed to the corresponding dione compounds. For example, compounds represented by Formula IX can be hydrolyzed to the corresponding cyclohex-2ene-1,4-dione, e.g. a compound of Formula VII, as described. If desired, the monoketals can be used as developing agent precursors Without hydrolysis first to the corresponding dione compound.

5,8-methano-2,3,4a,5,8,8a-hexahydro-naphtho 1 one- 4-monoketals can be prepared from the corresponding 5,8- methano-2,3,4a,5,8,8a-hexahydro-1,4-naphthoquinone as herein described. This can be represented, for example, by the following formulas:

(XII) wherein R, R and R" are the same or diiferent and each selected from hydrogen, halogen, alkyl, alkoxy and aryl, as described. This can be carried out by refluxing a compound of Formula XI with ethylene glycol in a suitable solvent, such as benzene, in the presence of p-toluenesulphonic acid with collection of water formed. a

Certain compounds within the described formulas are novel. These include compounds selected from the formulas:

(XIII) (I? A 3 (XIV) (I? B B BI! XV O R I and (XVI) wherein R, R' and R" are the same or diflFerent and each selected from hydrogen, halogen, alkyl, alkoxy and aryl, as described; A is lower alkyl; B, B and B are the same or different and each selected from hydrogen, halogen, alkyl, aryl, as described.

Examples of compounds Within Formulas XIII, XIV, XV and XVI are described herein. These include, for instance:

8 t-Butyl-5,8-methano-2,3,4a,5,8,8a-hexahydro-1,4-benzoquinone-4-monoethylene ketal Methyl-5,8-methano-2,3,4a,5,8,8a-hexahydro-1,4-benzoquinone-4-monoethylene ketal Dimethyl-S,8-methano-2,3,4a,5,8,8a-hexahydro-l,4-benzoquinone-4-monoethylene ketal Ethyl-5,8-methano-2,3,4a,5,8,8a-hexahydro-1,4-benzoquinone-4-monoethylene ketal Chloro-5,8-methano-2,3,4a,5,8,8a-hexahydro-l,4-benzoquinone-4-monoethylene ketal Methoxy-S,8-methano-2,3,4a,5,8,8a-hexahydro-1,4-benzoquinone-4-monoethylene ketal Phenyl-5,8-methano-2,3,4a,5,8,8a-hexahydro-1,4-benzoquinone-4-monoethylene ketal Any of the various isomers of the described compounds can be employed according to the invention. For example, in cases where cis and trans isomers exist, either one or both can be employed in the practice of the invention.

As described, a suitable embodiment of the invention is a photographic element having a coating containing a developing agent precursor selected from (a) cyclohex- 2-ene-l,4-dione developing agent precursors and (b) cyclohex-Z-ene-1-one-4-rnonoketal developing agent precursors. An especially suitable embodiment, however, comprises a photographic element having a coating containing a developing agent precursor which is a compound of Formula I as described.

The described developing agent precursors can be used in any suitable form for developing an exposed photographic silver salt. For example, the described precursors can be in any suitable form and location in and/or on a photographic element. It can be, for instance, in a photosensitive coating and/ or a coating contiguous to a photo graphic coating and/or in some other coating, such as an overcoat layer.

The described photographic element need not contain a photosensitive coating, but can be, for example, a support having a coating containing the described developing agent precursor which is contacted with a photographic element containing an exposed photosensitive coating in the presence of a suitable activator to effect development.

Another embodiment of the invention comprises a method of developing a latent image in an exposed photographic silver salt coating comprising contacting said silver salt coating with a developing agent precursor selected from (a) cyclohex-2-ene-1,4-dione developing agent precursors and (b) cyclohex-2-ene-l-one-monoketal developing agent precursors, in the presence of a development activator. This method wherein a compound of described Formula I is employed as a developing agent precursor is especially suitable.

Developing agent precursors of the invention can be activated employing any suitable means of activation. They can be activated by means of an alkaline material, such as an alkaline solution, and in suitable instances can be activated by heat and/or alkali. The described monoketals can be activated by suitable acid conditions and/or heat.

Organic activators, e.g. organic alkali and/ or inorganic activators, can be employed as activators. Suitable inorganic alkalis include alkali metal carbonates and alkali metal hydroxides, such as sodium carbonate, potassium carbonate, lithium carbonate, sodium hydroxide, potassium hydroxide, and lithium hydroxide. Suitable inorganic activators include amino alcohols, such as propanol amine, ethanol amine, imino-ethanols, amino alcohol sulfur dioxide addition products and the like.

The activator is typically employed in solution, such as an aqueous alkaline solution.

A wide range of pH can be employed with the com pounds of the invention. Monoketals described can be activated at pH of less than 7, e.g. about 2 to about 5, whereas cyclohex-Z-ene-1,4-diones can be activated at pH above 7, e.g. about 8.5 to about 14, perferably at least 10.

In some cases, such as in dry processing of photographic elements, it can be desirable to employ the described developing agent precursors in the presence of a development activator precursor and/or stabilizer precursor and/ or stabilizer activator precursor. For example, compounds which yield an activator and/or stabilizer and/or stabilizer activator upon application of heat and/or steam are useful. Useful activator precursors include betaines, tetramethylammonium compounds, sodium acetate, and suitable activator precursors set out in US. Pat. 3,220,846 of Tinker and Sagura, issued Nov. 30, 1965. Suitable stabilizer precursors are set out, for example, in US. Pat. 3,220,839 of Herz and Kalenda, issued Nov. 30, 1965.

The described developing agent precursors can be employed in a wide range of photographic compositions. They can be employed in any photographic composition in which a developing agent precursor is useful, such as in compositions for preparing coatings on a support for a photographic element; photosensitive compositions, such as photographic silver salt coatings; developer compositions; compositions containing combinations of silver salt processing agents, e.g. monobaths, as described, for example, in the book The Monobath Manual by Grant M. Haist (1966); in liquid or solid photographic processing compositions, such as in polar solvent solutions, and the like. They can be used in the form of a kit consisting of separate containers, such as packets, of processing components.

The described developing agent precursors can be, for instance, employed in hydrophilic colloid compositions employed in coatings for photographic elements, such as in photographic emulsion compositions.

The described developing agent precursors can be activated and used in any way that known hydroquinone developing agents are used.

It will be appreciated that the described developing agent precursors can be used alone or as mixtures. They can also be used as mixtures with other developing agents and/or precursors and as described can be used in any suitable form for developing an exposed photographic element. For instance, they can be used in an aqueous silver salt developer solution or liquid concentrate, as a component of a solid particulate developer precursor composition suitable for dissolving in an aqueous solvent, as a viscous developer composition containing various thickening agents, as a packaged component of a kit for mixing with various photographic processing agents or as a component of a fusible solid such as a solid comprising a homogeneous mixture of an alkylene oxide polymer and a developing agent precursor of the invention which melts above about room temperature. In such forms, they are useful in image transfer systems, diffusion transfer systems, dye-developer transfer systems, photographic ole"- ments designed for stabilization processing, elements designed for web processing, and color systems which involve a development step which is essentially black-and-white development, such as color reversal processes.

In a further embodiment of the invention, a developing agent precursor of the invention is dissolved in water in an amount of about 0.01 to about 30 grams per liter of water and the pH of the aqueous solution raised to about by the addition of alkali, e. g. sodium hydroxide, there by activating the precursor, after which an exposed photographic silver salt coating is developed by immersing or otherwise contacting the described exposed coating with the solution for a sufficient time to produce the desired density. A suitable pH range for such liquid developer, when alkaline, is from about 8.5 to about 14, preferably at least 10. Such liquid developing bath normally contains a preservative, such as sodium sulfite, alkali to activate the developing agent, and can also contain other materials, especially those known to be beneficial in developer compositions, such as sodium bromide as a restrainer, antifoggants, surfactants, and the like.

If desired, the compounds of this invention can be used both in a developing solution and in a coating on a photographic element.

In an especially useful embodiment of the invention where the described developing agent precursor is incorporated in a photosensitive element which is exposed and then contacted with an activator solution or bath, a bath comprising, for example, an aqueous solution containing about 1 percent by weight sodium hydroxide and about 5 percent by weight sodium sulfite is suitable for developing an exposed silver salt layer in about 30 seconds when the activator bath is at about 19 C. For example, an aqueous solution comprising about 4 percent by weight sodium carbonate and about 5 percent by Weight sodium sulfite produces development in about 30 seconds at about 19 C. Another aqueous activator solution comprising about 2 percent by weight sodium hydroxide and about 5 percent by weight sodium sulfite produces useful photographic images in a few seconds when heated at about 50 C. to about 60 C.

The described developer precursors can be incorporated in a photographic element employing any of the suitable coating methods employed in the photographic art. For example, the developer precursor compounds of our invention can be incorporated in an ordinary photographic silver halide emulsion, or colloidal dispersion of a waterpermeable hydrophilic colloid suitable for preparing an undercoat or an overcoat for such silver halide emulsion, by mixing a solution or dispersion of the precursor compound with the silver halide emulsion, or dispersion of hydrophilic colloid, prior to coating. For example, a developer precursor can be made up as an oil dispersion by stirring a solution of 10 grams of the developing agent precursor into 40 grams of warm tricresylphosphate, and then mixing this solution with grams of a 10 percent aqueous gelatin solution containing 10 cc. of a 5 percent aqueous solution of an alkylnaphthylene sodium sulfonate wetting agent. The resulting dispersion can be homogenized employing a colloid mill to produce a homogeneous colloid dispersion. Solvents other than tricresylphosphate can be employed, including any of the crystalloidal compounds described in Jelley and Vittum, US. Pat. 2,322,027, issued June 15, 1943. The resulting colloidal dispersion can then be added to an ordinary silver halide emulsion, or a dispersion of a water-permeable hydrophilic colloid, adapted for preparation of an undercoat for such silver halide emulsion.

Instead of adding the oil dispersion directly to the liquid silver halide emulsion or colloidal dispersion, it can be dried for storage purposes and then be reconstituted for use by merely mixing with Water.

The developing agent precursors of our invention can be adapted for addition to a liquid silver halide emulsion or colloidal dispersion by other means as well. Suitable methods will depend largely upon the solubility characteristics, particularly in water or polar solvents, of the particular precusors employed.

After addition of the dispersion or solution of the developing agent precursor substance to the liquid emulsion or colloidal dispersion, the mixture is stirred to assure uniform results, or passed through a blending device, such as a colloid mill. A uniform coating can be made on a suitable support and the coating dried.

The activator solutions may be applied to an exposed photographic element in any number of known ways, such as by dipping, spraying, or other suitable surface applications. If desired, a thickener can be added to the activator solution to increase the viscosity of the composition and make it more adaptable for continuous processing. Viscous compositions can then be removed by squeegeeing or water spraying.

The concentration of the developing agent precursor used in the invention will vary depending upon the particular chemical compound involved and, when used in a photographic element, the location of the compound Within the photographic element, and the like. That is, if the developing agent precursor of the invention is incorporated within the silver halide emulsion undergoing development, it may be desirable to use a somewhat different concentration than would be if the precursor were incorporated in a layer contiguous to the photographic silver halide emulsion. A useful concentration of developing agent precursor for incorporation in the emulsion is from about 0.01 to about 4.0 mole/mole of silver halide. A particularly useful range is from 0.1 to 2.0 moles/mole of silver halide, with especially useful results being obtained within the range of about 0.4 to 1.0 mole/mole of silver halide. For incorporation in other layers, somewhat larger concentrations can be tolerated without adverse effects.

Any photographic silver salt is suitable for use accord ing to the invention, especially photographic silver halides such as silver chloride, silver iodide, silver chlorobromide, silver chloroiodide, silver chlorobromoiodide, silver bromide and silver bromoiodide are especially useful. These can be employed without a binder and any of the conventionally employed water-permeable hydrophilic colloids can be employed in the silver halide emulsions, or in a layer contiguous thereto. Typical water-permeable hydrophilic colloids include gelatin, albumin, polyvinyl alcohol, agar agar, sodium alginate, hydrolyzed cellulose esters, hydrophilic polyvinyl copolymers, etc.

Other addenda can be employed in and/or on photographic elements employed in the invention, especially those addenda known to be beneficial in and/or on photographic elements. Silver halides employed can be chemically sensitized with compounds of the sulfur group, e.g. sulfur sensitizers, selenium sensitizers, tellurium sensitizers, noble metal salts, such as gold or reduction sensitiZers with reducing agents or combinations of such sensitizers. The silver halide emulsions of this invention may contain spectral sensitizers, such as the cyanines, merocyanines, styryls, hemicyanines, speed-increasing compounds, such as polyalkylene glycols, onium salts and thioethers, stabilizers such as azaindenes, cadmium and other divalent salts, mercury compounds, azoles and mercaptants, coating aids, such as nom'onic, anionic and amphoteric surfactants, etc.

The described developing agent precursors are useful for developing a wide range of photographic emulsions. In addition to being useful with X-ray and other nonoptically sensitized emulsions, they can also be used with orthochromatic, panchromatic, infrared sensitive emulsions, and lith type emulsions which usually are developed to high contrast in developing solutions having a low concentration of sulfite ions. They can be added to the emulsion before or after any sensitizing dyes if desired.

The described developing agent precursors can be employed with photographic elements intended for color photography, for example, containing color-forming couplers or photographic elements to be developed by solutions containing couplers or other color-generating materials, photographic emulsions of the mixed-packet type, such as described in Godowsky, U.S. Pat. 2,698,794, issued Jan. 9, 1955; or emulsions of the mixed-grain type, such as described in Carroll and Hanson, U.S. Pat. 2,592,243.

An auxiliary developing agent can be employed with the described developing agent precursors if desired. For example, an auxiliary developing agent can be added either to a developer solution, to a silver halide emulsion layer, or to a hydrophilic layer contiguous thereto, although it is not necessary to do so in most cases. Typical auxiliary developing agents include 3-pyrazolidone developing agents, such as those set out in British Pat. 930,572 and British Pat. 958,678. Such pyrazolidone developing agents can contain an acyl or acyloxy substituents which can be hydrolyzed by treatment with the above activator solutions, thus being also a developing agent precursor, to produce the desired auxiliary developing compound. Other photographic developing agents which can be employed alone with the precursors of the invention or in combination with 3-pyrazolidone developing agents include, for example, polyhydroxy benzenes, such as hydroquinone developing agents, e.g. hydroquinone, alkyl substituted hydroquinone, such as t-butyl hydroquinone, methylhydroquinone, dimethylhydroquinone, catechol and pyrogallol; chloro substituted hydroquinones, such as chlorhydroquinone, or dichlorohydroquinone; alkoxy substituted hydroquinone, such as methoxy or ethoxy hydroquinone; aminophenol developing agent such as N-methyl-p-aminophenol and 2,4-diaminophenols; ascorbic acid developing agents; N-methylp-aminophenyl sulfate, pyrazolones such as 4aminopyrazolone; etc.

The concentration of auxiliary developing agent can be varied, and, of course, no auxiliary developing agent need be employed unless so desired. Useful concentrations of auxiliary developing agents vary from about 0.01 mole to about 2.0 moles per mole of developing agent. Depending upon the particular auxiliary developing agent precursor employed, larger or smaller quantities can be used.

The developing agent precursors of this invention can be used in compositions intended for use in diffusion transfer processes which utilize underdeveloped silver halide in non-image areas of a negative to form a positive by dissolving undeveloped silver halide and precipitating it on a receiving layer in close proximity to the original silver halide layer. Such processes are described, for instance, in Rott, U.S. Pat. 2,353,014, issued June 20, .1944, and Land, U.S. Pat. 2,584,029, issued Jan. 29, 1952; 2,698,236, issued Dec. 238, 1954, and 2,543,181, issued Feb. 27, 19 51; and Yackel et al., U.S. Pat. 3,020,155, issued Feb. 6, 1962. They can also be used in color transfer processes which utilize the diffusion transfer of an image-wise distribution of developer, coupler or dye, from a light-sensitive layer to a second layer, while the two layers are in close proximity to one another. Color processes of this type are described in Land, U.S. Pats. 2,559,643, issued July 10, 1951 and 2,698,798, issued Jan. 4, 1955; Land and Rogers, Belgian Pats. 554,933 and 554,934, granted July 16, 1957, and 544,935, granted Aug. 12, 1957; Yutzy, U.S. Pat. 2,756,142, granted July 24, 1956, and Whitmore and Mader, U.S. Pat. application Ser. No. 734,141, filed May 9, 1958.

The developing agent precursors of the invention can, for instance, be employed in photographic dye developer image transfer systems, such as described in U.S. Pat. 3,232,915Weyerts et al., issued May 31, 1966; U.S. Pat. 2,559,643Land, issued July 10, 1951; and U.S. Pat. 2,698,798-Land, issued Jan. 4, 1955. In such systems, a dye diffusion transfer takes place. Compounds which contain in the same molecule, both the chromophoric system of a dye and a photographic silver develop ing moiety, have been described as useful compounds in photographic elements for preparing color images by diffusion transfer processes. Such compounds are commonly called dye developers. Photographic elements containing such dye developers generally comprise a plurality of photosensitive silver halide layers wherein each of the layers is selectively sensitized to a different region of the spectrum. A dye developer is typically positioned contiguous to the silver halide in each of such layers. Such a photographic element can according to the invention contain a described developing agent precursor in one of the layers of the element, such as in a gelatin overcoat layer. The photographic element after exposure can be processed with an alkaline composition with the latent image being developed in the image areas with the dye developers, this development immobilizing the dye developers in such image areas. The dye developers in the unexposed image areas diffuse to the surface imagewise and are transferred to a reception layer or 13 receiving sheet to form a positive multicolor image. Similarly, such dye diffusion transfer systems can be used to prepare single color transfer prints.

The developing agent precursors within the scope of the invention can typically be employed as auxiliary developing agent precursors in dye developer image transfer elements and processes.

They may also be used in emulsions intended for use in a monobath process such as described in Haist et al., US. Pat. 2,875,048, issued Feb. 24, 1959, and in web-type processes, such as the one described in Tregillus et al., US. Pat. No. 3,179,517.

EXAMPLE 1 This example illustrates preparation of reduced cyclopentadiene-l,4-benzoquinone adducts which can be employed for preparing described developing agent precursors.

The reduced adducts are each prepared in the same manner. One example is described here. A solution of 37.6 g. (0.2 mole) of the cyclopentadiene-toluquinone adduct in 200 ml. of acetic acid is added at room temperature to a stirred suspension of .40 g. of zinc dust in 200 m1. of water. The temperature rises rapidly from 24 to 50 C. After fifteen minutes of stirring the temperature falls to 35; longer reduction times are avoided. The stirred suspension is diluted with 200 ml. of water, chilled to room temperature and then 200 ml. of chloroform is added and stirring is continued for 2 minutes. The resulting suspension is filtered and the chloroform extract separated. The extract is washed twice with water, once with 5% sodium bicarbonate and again with water. After drying over anhydrous magnesium sulfate, the extract is evaporated in a rotary evaporator to a thick oil which crystallizes on chilling. The desired 2-methyl-5,8-methano- 2,3,4a,5,8,8a-hexahydro-1,4-naphthoquinone, M.P. 95- 7 C., is recrystallized from ethanolligroin.

EXAMPLES 2-10 Following the procedure of Example 1, the results given below are obtained.

B. Reduced adduct Ex. A. Cyclopentadiene adduct with- M. P., C.

2- 1,4-benzoquinone 24-26 (B.P. 1315 C. at; 0.6

mm. Hg absolute). 3. 2,5-dimethyl-l,4-benzoquinone 73-74. 4. 2,3,5-trimethyl-1,4-benzoquinone. Oil. 5. 2,3-dimethy1-1,4-benzoquinone 57-70. 6'. 2-isopropy1-1,4-benzoquinone. 14-16. 7- 2-t-butyl-l,4-benzoquinone 114-115 8. 2-phenyl-1, l-benzoquinone- 110-111 9. 2-methoxy-1,4-benzoquinone Oil.

a This is a mixture of cisand trans-isomers.

b Comprises a cis-isomer, M.P. 9192 0.; a cis-isomer, M.P. 135 C., and a trans-isomer, M.P. 84-85 C. The 9192 C. isomer is isomerized to the others by alumina.

The pyrolytic decomposition or so-called retrograde Diels-Alder reaction is, in general, carried out in the same manner for all of the reduced adducts. Minor changes in temperature, pressure and column length are employed for each example. The yields of products are good in most cases.

EXAMPLE 10 for extended periods when kept in stoppered Pyrex flasks in the dark at 10 C.

The UV measurements are made in hexane and the IR spectra in carbon tetrachloride.

These cyclohexenediones are active dienophiles and are useful in many diene syntheses. For example, cyclohex-Z- ene-1,4-dione reacts readily with cyclopentadiene to reform the reduced adduct of Example 2.

EXAMPLE 20 Two grams of cyclohex-2-ene-1,4-dione is dissolved in benzene and treated with five grams of cyclopentadiene. After standing overnight, the solvent is removed and the residue purified by chromatography on silica gel. The product is an oil having an IR spectrum identical to the product of Example 2.

EXAMPLE 21 The 2 and/or 3-substituted 5,6-dichlorocyclohex-2-ene- 1,4-dione development agent precursors of the invention are prepared as described in the literature. Several typical examples are listed below: I

R2 R3 M.P., C

CH; -H 131-133 OH(CH3)2 H 86-88 CH3 -CH3 189-191 -06H5 129-130 EXAMPLE 22 The three pure isomers, i.e. cis-isomers, M.P. 91-92" C. and 135 C. and trans-isomer M.P. 84-85 C. of 2,3-dimethyl-5,8-methano-2,3,4a,5,8,8a-hexahydro 1,4 naphthoquinone in 1:1 ligroin-ether are stirred with a 20-30 weight excess of alumina for at least 18 hours. The alumina is filtered off and solvent removed in vacuo. The crude and recrystallized products are examined by infrared spectroscopy which indicates each product to be a mixture of the cis and trans isomers, M.P. 91-92 C. and M.P. 84-85 C. respectively.

EXAMPLE 23 The crude product (30 g.) from the reduction of the 2,3-dimethylbenzoquinone-cyclopentadiene adduct is distilled at 15 mm. Hg pressure. The product (18 g.) boils at 86-94" C. The liquid is diluted with ligroin (10 ml.) and chilled. The crystals are filtered off and shown by M.P. and IR spectrum to be identical with the dimethylcyclohex-2-ene-1,4-dione obtained in Example 5. The NMR spectrum shows this material to be the trans isomer.

The mother liquid is concentrated and distilled at 15 mm. Hg pressure. The NMR spectrum of the liquid indicates that it is composed of 40 percent of the trans isomer and 60 percent of the cis isomer.

15 EXAMPLE 24 H *Crude product from the reduction of the 2,3-dimethylous sodium carbonate solution having a pH of about 11.

The results are set out in following Table I.

TABLE I Developer solution Alkaline activator Photograph- Photograph- Developing agent 10 speed Gamma Fog m: ic speed Gamma Fog Dunn! i i-tit;rtyaaaa eteri arant:""*3: 32 233 :ii i3 162 "2.% .32 2.96 5-i-propy1-cyclohex-2-ene-l,4-di0ne. 68 6.7 .10 4.0 123. 4.9 .30 3. 8t

benzoquinone cyclopentadiene adduct (60.6 g.) (0.3 r EXAMPLE 28 mole), is taken up in 100 ml. of hot ligroin, filtered and This is a com arative exam 1e demonstratin advam allowed to stand 24 hours at room temperature. The crystages of the invengon p g tals formed f t to y f i The process set out in Example 28 is repeated with the M 75-81 Thls matena} 1s recrystaihzed P Z exception that 286 mg. per square foot of support of t1onalt1mesfrom 50-ml. portions of ligrom to yield .5 g. 4, methylphenyl hydroquinone is employed in Place of of pure 1somer c1s-endo-2,3-d1methyl-5,8-methano-2,3,4a, the described 1 c 1 h s s 8a-hexah drO-l. 4-na htho uinone M.P. 91-92: c. y ex 9 y i P q The following results are obtained employing the de- EXAMPLE veloper solution and activator solution described in Ex- The product from reduction of the 2,3-dimethyl benzoample quinone-cyclopentadiene adduct (80 g.) is chromato- 25 DEVELOPING SOLUTION graphed on alumina in 1:1 li groin/ether- Prior q l Photographic speed 71 tography analysis shows the presence of h 1 Gamma 6.1 of Example 25, MP. 91-92 C. Careful elution glves f Fog .16 tions totalling 7 o g., none of which contains the g i D 4.0 MP. 91-92 C. The eluted material is recrytsa ize seven times from ligroin to give 5 g. of cis-exo 2,3-di- ACTIVATOR SOLUTION methyl 5,8 methane 2,3,4a,5,8,8a hexahydro 1,4- Photographic speed 100 naphthoquinone, MP. 135 C- Gamma r Fog .24 R e m om mo er 1 n1 of E lfaiih gl e 22, 22; tr nsgfil imthyldji-methano lii, i i i thait develgpmg ageilt precurso. of 4a 5,8 8'EL-hEX3hYdIO-1 4-naphthoquinone, M.P. 8485 C- 3 well Ion .Provl 6 higher P oiqgmphlc SPeed, hlgher a gamma and higher maximum density when incorporated EXAMPLE 27 40 in a coating of a photographic element which is developed One gram of each of the developing agent precursors by Contact with an activator listed 'below is dissolved in tWo grams of tricresyl phos- EXAMPLE 29 phate, which 1s then added to a gelatin solut1on containing a dispersing agent. The mixture is then colloid milled. one am of Y Y -6I1 -1,4-d10ne is (118- The resulting dispersions are added to separate portions solved m 1 grfim Q tncl'esyl P p dlspersed and of a gelatin solution containing a hardener and spreading coated as descnbed m ExamRle 28 at 185 8- P Square agent and coated on a cellulose acetate film support at of PP A control wlthollt oping agent and mg. gelatin per square foot of support. The developh a 'methylphenyl hydroqumone dlspersion as ing agent percursors are coated at the concentrations Scnbedm Example 28 are also coated listed below. 50 Compound: Milligrams of compound/ft.

Mg. dev./ft. Control Control 4-methylphenyl hydroquinone 220 5-?.buty1-cyc10he -2-1,4-di0ne 216 S-t-butyl-cyclohex-Z-ene-1,4-dione 185 s'l'propyl'cyclohex'z'ene'l4'dlone 240 The silver bromoiodide emulsion set out i Example 28 A silver bromoiodide gelatin emulsion containing apis coated over this layer at 298 mg. Ag and 400 mg. gelaproximately 2.5 mole percent iodide is coated over thlS tin per square foot. A gelatin overcoat containing 50 mg. layer at 425 mg. Ag and 400 mg. gelatin per square foot. of gelatin per square foot is applied thereover. The re- A gelatin overcoat is appled which contains 50 mg. of suiting coatings are exposed and processed as described gelatin per square foot. The resulting coatings are eX- in Example 28. Similar results are obtained. The resultposed sensitometrically and divided into two equal parts ing developed image has good incubation stability. or sets of coatings. The first set of coatings, including a control having no incorporated developing agent or devel- EXAMPLE 30 oping agent precursor, is developed by immersion for two minutes in a developer solution having the following com- The Prcfcedure Set out In Example 28 is repeated With Position: the exception that 152 mg. per square foot of 5,6-dimeth- Grams yl cy clohex-2-ene-1,4-dione is employed in place of the N th l i h l lf t descnbed t-butyl cyc1ohex-2-ene-1,4-dione. Sodium sulfite desiccated 45 The following results are obtained: Hydroquinone 12.0 Sodium carbonate, monohydrated 80.0 DEVELOPER SOLUTION Potassium bromide 2.0

Photographic speed 22 Water to make 1 liter. Gamma 7.1 The second set of coatings is developed by immersion for Fog .08 one minute in an activator solution consisting of an aque- D 4.0

17 ACTIVATOR SOLUTION Photographic speed 36 Gamma 2.54 Fog .40 D 2.06

The resulting developed image has good incubation stability.

EXAMPLE 31 5,6-dichlorocyclohex-2-ene-1,4-dione is used in place of the described cyclohexy-2-ene-1,4-diones of Example 28. Similar results are obtained as in Example 28.

EXAMPLE 32 2 phenyl 5,8 methano 2,3,4a,5,8,8a-hexahydro-1, 4-naphthoquinone (50.4 g.), ethylene glycol 12.4 g.) and p-toluene-sulfonic acid (0.1 g.) in benzene (500 ml.) are heated under reflux for 18 hours. The Water formed during the reaction is collected in a Dean-Stark trap. Pyridine (2 ml.) is added to the benzene solution. After being Washed with water, the benzene layer is dried (MgSO and evaporated to dryness. The product is recrystallized from ligroin to give the desired monoketal, i.e. 2-phenyl- 5,8-methano 2,3,4a,5,8,8a hexahydro 1,4 naphthoquinone-4-monoethylene ketal, M.P. 177-178 C.

EXAMPLE 3 3 2-methyl-5,8-methano 2,3,4a,5,8,8a hexahydro-1,4- naphthoquinone-4-monoethylcne ketal is prepared in an analogous manner to that set out in Example 33 and has M.P. 69-70 C.

EXAMPLE 34 6-phenylcyclohex 2 ene 1 one-4-monoethylene ketal is distilled at 20 mm. pressure with the oil bath temperature at 240 C. from the product of Example 33. The crude product distills at 164 C. and is recrystallized from light petroleum (B.P. 6080 C.) to give the desired ketal M.P. 87-88 C. (10.5 g., 85%).

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. A photographic element comprising a support, a photographic silver salt and a developing agent precursor which is (a) a cyclohex-2-ene-1,4-dione developing agent precursor, or (b) a cyclohex-Z-ene-1-one-4-monoketal developing agent precursor.

2. A photographic element as in claim 1 wherein said developing agent precursor is a compound of the formula:

:0 or C 3. A photographic element as in claim 1 comprising a photographic silver halide gelatino emulsion coating.

4. A photographic element as in claim 1 comprising a 3-pyrazolidone developing agent.

5. A photographic element as in claim 1 wherein said developing agent precursor is (a) t-butyl cyclohex-Z-ene-1,4-dione,

(b) dimethyl cyclohex-Z-ene-1,4-dione,

(c) methyl cyclohex-2-ene-1,4-dione, or

(d) dichloro cyclohex-Z-ene-l,4-dione.

6. A photographic element as in claim 1 comprising an antifoggant.

7. A photographic element as in claim 1 comprising a development activator precursor. I

8. A photographic element as in claim 1 comprising an auxiliary developing agent.

9. A method of developing a latent image in a photographic element comprising a support and an exposed photographic silver salt comprising contacting said photographic silver salt With a developing agent precursor which is (a) a cyclohex-2-ene-1,4-dione developing agent precursor, or (b) a cyclohex-Z-ene-1-one-4-monoketal developing agent precursor, in the presence of an alkaline development activator.

10. A method as in claim 9 comprising contacting said photographic silver salt with a developing agent precursor of the formula:

wherein R, R and R" are each hydrogen, halogen, alkyl, alkoxy or aryl; and Z is in the presence of an alkaline development activator.

11. A method as in claim 9 wherein said photographic element contains said developing agent precursor.

12. A method as in claim 9 comprising a dry development process.

13. A method as in claim 9 comprising contacting said photographic silver salt with a solution of said developing agent precursor.

14. A method as in claim 9 comprising contacting said photographic element with an aqueous alkaline solution.

15. A method as in claim 9 comprising contacting said photographic element with an alkaline solution containing a photographic silver salt developing agent.

16. A method as in claim 9 wherein said developing agent precursor is (a) t-butyl cyclohex-2-ene-1,4-dione,

(b) dimethyl cyclohex-Z-ene-1,4-dione,

(c) methyl cyclohex-2-ene-1,4-dione, or

(d) dichloro cyclohex-2-ene-1,4-dione.

17. A photographic composition comprising a hydrophilic colloid, a developing agent precursor which is (a) a cyclohex-2-ene-1,4-dione developing agent precursor or (b) a cyclohex-Z-ene-1-one-4monoketa1 developing agent precursor and a photographic silver salt.

18. A photographic composition as in claim 17 comprising a photographic emulsion.

19. A photographic composition as in claim 17 comprising a photographic silver halide emulsion.

References Cited Journal of the American Chemical Society, Nov. 5, 1965, p. 4971, Cyclohex-2-ene-4,1-Dione, Garbisch.

NORMAN G. TORCHIN, Primary Examiner J. L. GOODROW, Assistant Examiner U.S. Cl. X.R. 96-95 

